[Beowulf] Opteron performance
bill at cse.ucdavis.edu
Wed Dec 8 04:08:46 EST 2004
On Tue, Dec 07, 2004 at 03:36:30PM -0800, Joel Jaeggli wrote:
> On Tue, 7 Dec 2004 pesch at attglobal.net wrote:
> >Where can I find a decent comparison betwenn Opteron and Athlon64
> functionaly the only difference betten the two is memory bandwidth and the
> number of ht ports.
Er, it's a bit more complicated than that.
Athlon 64's are available in 3 flavors:
s754 athlon 64s have a 64 bit memory bus (unregistered memory, 1 less cycle)
s939 athlon 64s have a 128 bit memory bus (unregistered memory, 1 less cycle)
s940 athlon 64s have a 128 bit memory bus (registered, 1 more cycle)
The FX is available in both s939 and s940, but are "unlocked" so you
can change the multiplier (useful mostly for overclocking).
Athlon 64s have 2 cache sizes, 512K and 1024K. Be careful often the
same cpu rating (like the athlon 64 3200) are available in 2 cache sizes
and 2 clock speeds.
So the main performance differences are 1/2 the memory bandwidth for
s754 chips, and 1/2 the cache size for some athlon 64's. The effect
of either will depend on the application.
AFAIK, the s939 athlon 64's have 3 HT's just like the opteron, but none
of them are coherent, so you can't run SMP with them.
Computational Science and Engineering
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